Earth is reaching its breaking point, U scientists warn

U scientists join others in warning that people may have the planet near environmental breaking point.

By TOM MEERSMAN, Star Tribune

Last update: September 23, 2009 - 11:52 PM

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Human pressure is pushing the planet's food, water and environmental systems to the breaking point, say more than two dozen leading scientists, including two from the University of Minnesota.

Their conclusions, published Wednesday in an unusual paper in the journal Nature, are the first attempt to define the physical and biological limits of Earth as nations increase development and populations.

"For lack of a better phrase, the Earth becomes a bit more like Humpty Dumpty," said report co-author Jon Foley, director of the University of Minnesota's Institute on the Environment. "You push it, it falls over, and it breaks. You can't put it back together again."

If systems unravel, he said, the planet will survive but there could be huge costs and disruption in the world's economy.

Foley said the unprecedented study, "Planetary Boundaries: A Safe Operating Space for Humanity," is not a typical research paper in which a small team of scientists focuses on a narrow band of research. The idea emerged, he said, when 28 scientists in different fields started to notice the same thing: Ecosystems can collapse when put under too much pressure.

As a climatologist, Foley said that he watched average global temperatures inch up very slowly over the years, and then ice sheets and glaciers started to disappear rather rapidly. "Suddenly we began to lose the integrity of the climate system," he said.

The study defines nine subsystems that need to be watched closely to avoid irreversible damage. They include climate change, global freshwater use, ocean acidification, species extinction, ozone depletion, conversion of natural land to cropland, chemical pollution, atmospheric pollution, and nitrogen and phosphorus additions to the biosphere and oceans.

Of the nine systems, climate change, species extinction and nitrogen additions are changing at rates faster than scientists believe is sustainable, the paper states.

Peter Snyder, an atmospheric scientist and co-author at the University of Minnesota, said it's clear that the planet is under unprecedented pressure from developed nations, with more to come from rapidly growing countries such as India and China that are consuming more food, energy and other products.

"If you exceed enough boundaries, which is the direction we're heading, then you have a real problem and you've pretty much undermined the capacity of the Earth to sustain us," he said.

The Associated Press contributed to this article. Tom Meersman • 612-673-7388

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